Ecg Criteria

Front 1

Normal ECG

Back 1

•No rate, rhythm, or axis abnormalities
•P wave (normal axis: 0-75 degrees; i.e. upright in leads I and II), PR interval (duration 120-200 ms), QRS complex (normal axis: -30 to 105 degrees; duration < 120 ms), ST segment (usually isoelectric with less than 1 mm of elevation/depression in limb leads), and T wave (upright in I, II, V3-V6) are normal configuration and/or duration.

Front 2

Incorrect Lead Placement

Back 2

•Reversal of right and left limb leads, resulting in negative P wave and QRS axis in leads I and aVL, and upright P wave and QRS axis in aVR (limb lead reversal can mimic dextrocardia, but dextrocardia cannot exist if the precordial leads appear normal; i.e. dextrocardia would cause reverse R wave progression in the precordial leads)
•Reversal of two precordial leads, resulting in a sudden decrease in R wave progression with a marked return in the R wave on the ensuing precordial lead.

Front 3

Right Atrial Enlargement

Back 3

•P wave > 2.5 mm tall in leads II, III, and aVF (termed P-pulmonale), or
•P wave greater than 1.5 mm tall in leads V1 or V2

Front 4

Left Atrial Enlargement

Back 4

•Terminal protion of P wave in lead V1 > 1 mm deep and > 0.04 seconds in duration (one 'little box' wide and deep on a standard 25 mm/s ECG tracing), or
•Notched P wave with duration greater than 0.12 seconds in inferior leads (termed P-mitrale).

Front 5

Sinus Arrhythmia

Back 5

•Normal P wave axis (0 to 75 degrees; i.e. upright in leads I and II)
•P-P interval varies by > 10% or 0.16 seconds.

Front 6

Sinus Pause

Back 6

•Greater than 2 second pause without a P wave

Front 7

Sinoatrial Exit Block

Back 7

Sinoatrial (SA) exit block is simply the failure of the sinus impulse to escape the SA node and enter the atrial conduction tissue. Much like atrioventricular block (heart block), there are 4 possible types of SA block: First Degree, Second Degree Mobitz Type I, Second Degree Mobitz Type II, Third Degree.

Front 8

Atrial Parasystole

Back 8

•Seen when a seconday pacemaker is working in parallel with the sinoatrial (SA) node
•Results in two different P waves (one from the SA node and one parasystolic)
•The origin of the parasystolic P wave is protected from SA node depolarization by the presence of an entrance block

Front 9

Atrial Tachycardia

Back 9

•Abnormal P waves different in morphology from sinus P waves
•Differs from atrial premature complexes in that there are at least 3 beats in succession
•Typical atrial rate is 100 to 180 beats per minute
•Usually results in a normal QRS complex (similar to that seen in sinus rhythm) following each P wave, unless the QRS complex is aberrantly conducted

Front 10

Multifocal Atrial Tachycardia

Back 10

•Must have at least 3 different P wave morphologies
•Atrial rate > 100 per minute
•Varying P-P and P-R intervals

Front 11

SVT

Back 11

•Regular rhythm with ventricular rate > 100 per minute
•QRS complex is usually narrow unless aberrant conduction exits
•P waves may be buried in the QRS complex, immediately following with a short R-P interval (< 0.09 seconds) or a long R-P interval.

Front 12

Atrial Flutter

Back 12

•Macro-reentrant electrical activity in the atrium resulting in rapid regular flutter (or 'F') waves
•Flutter waves typically occur at a rate of 240 to 340 per minute
•The ventricular rate can be irregular if a variable AV block exists

Front 13

Atrial Fibrillation

Back 13

•Absent P waves and irregular ventricular rate
•Atrial activity is represented by fibrillatory (or 'f') waves having no organized pattern

Front 14

AV Junctional Escape Complexes

Back 14

•Usually narrow QRS complex following a previously conducted beat at a coupling interval that corresponds to a rate of 40 to 60 per minute
•A P wave, with typically a superior and leftward axis, if seen, may be seen immediately before or after the QRS complex
•Termed 'escape' complexes because they act as a backup pacemaker of the heart in the setting of severe sinus node dysfunction, sinus pauses, or high degree AV block.

Front 15

AV Junctional Tachycardia

Back 15

•A consistently occuring, usually narrow, QRS complex at a rate of 40 to 60 per minute (junctional rhythm) or > 60 per minute (junctional tachycardia)
•The QRS complex can be wide in the presence of aberrancy or a pre-existing intraventricular conduction disturbance
•A P wave, with typically a superior and leftward axis, if seen, may be seen immediately before or after the QRS complex.

Front 16

Sinus Pause

Back 16

•Greater than 2 second pause without a P wave

Front 17

Sinoatrial Exit Block

Back 17

Sinoatrial (SA) exit block is simply the failure of the sinus impulse to escape the SA node and enter the atrial conduction tissue. Much like atrioventricular block (heart block), there are 4 possible types of SA block:
•First Degree is not detectable on the surface ECG
•Second Degree Mobitz Type I is characterized by group beating, a shortening P-P interval with a constant P-R interval, and a P-P pause interval less than twice the usual P-P interval
•Second Degree Mobitz Type II is characterized by a constant P-P interval with a P-P pause interval being approximately a precise multiple (within 0.10 seconds) of the usual P-P interval
•Third Degree is not detectable on the surface ECG.

Front 18

Atrial Parasystole

Back 18

•Seen when a seconday pacemaker is working in parallel with the sinoatrial (SA) node
•Results in two different P waves (one from the SA node and one parasystolic)
•The origin of the parasystolic P wave is protected from SA node depolarization by the presence of an entrance block

Front 19

Atrial Tachycardia

Back 19

•Abnormal P waves different in morphology from sinus P waves
•Differs from atrial premature complexes in that there are at least 3 beats in succession
•Typical atrial rate is 100 to 180 beats per minute
•Usually results in a normal QRS complex (similar to that seen in sinus rhythm) following each P wave, unless the QRS complex is aberrantly conducted

Front 20

Multifocal Atrial Tachycardia

Back 20

•Must have at least 3 different P wave morphologies
•Atrial rate > 100 per minute
•Varying P-P and P-R intervals

Front 21

SVT

Back 21

•Regular rhythm with ventricular rate > 100 per minute
•QRS complex is usually narrow unless aberrant conduction exits
•P waves may be buried in the QRS complex, immediately following with a short R-P interval (< 0.09 seconds) or a long R-P interval.

Front 22

Atrial Flutter

Back 22

•Macro-reentrant electrical activity in the atrium resulting in rapid regular flutter (or 'F') waves
•Flutter waves typically occur at a rate of 240 to 340 per minute
•The ventricular rate can be irregular if a variable AV block exists

Front 23

Atrial Fibrillation

Back 23

•Absent P waves and irregular ventricular rate
•Atrial activity is represented by fibrillatory (or 'f') waves having no organized pattern

Front 24

AV Junctional Escape Complexes

Back 24

•Usually narrow QRS complex following a previously conducted beat at a coupling interval that corresponds to a rate of 40 to 60 per minute
•A P wave, with typically a superior and leftward axis, if seen, may be seen immediately before or after the QRS complex
•Termed 'escape' complexes because they act as a backup pacemaker of the heart in the setting of severe sinus node dysfunction, sinus pauses, or high degree AV block.

Front 25

AV Junctional Tachycardia

Back 25

•A consistently occuring, usually narrow, QRS complex at a rate of 40 to 60 per minute (junctional rhythm) or > 60 per minute (junctional tachycardia)
•The QRS complex can be wide in the presence of aberrancy or a pre-existing intraventricular conduction disturbance
•A P wave, with typically a superior and leftward axis, if seen, may be seen immediately before or after the QRS complex.

Front 26

Ventricular Parasystole

Back 26

•Seen when a ventricular focus stimulates premature ventricular contractions (PVCs) at a constant rate (or multiple of the constant rate)
•Results in the presence of sinus rhythm alongside a secondary rhythm of PVCs (i.e ventricular parasystolic rhythm)
•An entrance block often exists at the origin of the parasystolic PVC, preventing sinus-stimulated ventricular depolarization from reseting the ectopic ventricular focus.

Front 27

Accelerated Idioventricular Rhythm (AIVR)

Back 27

•Regular or mildly irregular ventricular rhythm with a rate of 60 to 110 per minute
•Morphology of QRS complex is typically wide and similar to that of premature ventricular contractions
•Often will be seen in the setting of myocardial reperfusion following infarction and is felt to be benign.

Front 28

Ventricular Escape Rhythm/complex

Back 28

•Regular or mildly irregular ventricular rhythm with a rate of 20 to 40 per minute
•Morphology of QRS complex is typically wide and similar to that of premature ventricular contractions

Front 29

AV Block, 1st Degree

Back 29

•P-R interval greater than or equal to 0.20 seconds
•Each P wave is followed appropriately by a QRS complex

Front 30

AV Block, 2nd Degree Mobitz type 1 (Wenckebach)

Back 30

•Progressive prolongation of the PR interval until a P wave is blocked
•R-R interval of non-conducted beat must be less than 2 times the P-P interval (otherwise, higher degree of AV block exists)
•Will give the appearence of grouped beating.

Front 31

AV Block, 2nd Degree type 2 (Mobitz 2)

Back 31

•Regular sinus or atrial rhythm with intermittent non-conducted P waves and no evidence of premature atrial contractions
•Constant P-R interval exists with all conducted beats
•The R-R interval of non-conducted beat is equal to two P-P intervals

Front 32

AV Block 2:1

Back 32

•Regular sinus or atrial rhythm with intermittent non-conducted P waves and no evidence of premature atrial contractions
•Constant P-R interval exists with all conducted beats
•The R-R interval of non-conducted beat is equal to two P-P intervals

Front 33

AV Block, 3rd Degree

Back 33

•Complete failure of atrial impulses to pass through the AV node and stimulate ventricular activity
•Results in constant P-P intervals and R-R intervals, but the atrial and ventricular rhythms are independent of each other
•Atrial rate is typically faster than the ventricular rate, as the ventricular rate is driven by either a junctional rhythm, ventricular escape complex, or a ventricular pacemaker

Front 34

Low Voltage

Back 34

•Entire amplitude of the QRS (R + S wave) must be < 5mm in all limb leads or < 10mm in all precordial leads

Front 35

Left Axis Deviation

Back 35

•Mean QRS axis between -30 and -90 degrees

Front 36

Right Axis Deviation

Back 36

•Mean QRS axis between 100 and 270 degrees

Front 37

Electrical Alternans

Back 37

•Beat to beat variability in the amplitude or direction of the P, QRS, and/or T waves

Front 38

LVH

Back 38

•Cornell Criteria: R wave in avL + S wave in V3 > 28mm in males or > 20mm in females
•Sokolow-Lyon Criteria: S wave in V1 + R wave in V5 or V6 > 35mm
•Sokolow-Lyon 'Stand-alone' Criteria: R wave in aVL > 11mm

Front 39

RVH

Back 39

•Mean QRS axis greater than or equal to 100 degrees (i.e. Right Axis Deviation)
•R/S ratio in V1 > 1, R/S ratio in V5 or V6 < 1, qR complex in V1, or R wave > 7mm in V1
•Secondary ST-T segment changes (ST depression or T wave inversion) in right precordial leads

Front 40

Combined Ventricular Hypertrophy

Back 40

•Exists when criteria for both isoloated left (LVH) and right ventricular hypertrophy (RVH) are met
•Should be suspected when criteria for LVH is present but QRS axis is > 90 degrees or criteria for right atrial enlargement exist
•R/S ratio approximately equal to 1 in both V3 and V4 (Kutz-Wachtel phenomenon)

Front 41

RBBB, complete

Back 41

•Prolonged QRS duration greater than or equal to 120 ms in adults, greater than 100 ms in children ages 4 to 16 years, and greater than 90 ms in children less than 4 years of age
•rsR', rsr', or rSR' complexes in V1 or V2, with the secondary R wave (r' or R') usually wider than the initial R wave (r); a minority of patients may have a wide and often notched R wave pattern in lead V1 and/or V2
•S wave of greater duration than R wave or > 40 ms in leads I and V6 in adults
•Normal R peak time in leads V5 and V6 but > 50 ms in lead V1
•Of the above criteria, the first 3 should be present to make the diagnosis. When a pure dominant R wave with or without a notch is present in V1, the 4th criteria should be satisfied.

Front 42

RBBB, incomplete

Back 42

•QRS duration between 110 and 120 ms in adults, between 90 and 100 ms in children between 4 and 16 years of age, and between 86 and 90 ms in children less than 8 years of age
•Other criteria are the same as for complete RBBB

Front 43

Left Anterior Fasicular Block

Back 43

•Mean QRS axis between -45 degrees and -90 degrees with mean QRS duration < 120 ms
•Typically qS complex in lead I and rS complexes in leads II and III
•qR pattern in lead aVL with delay of > 45 ms from beginning of QRS complex to peak of R wave in lead aVL
•Absence of other causes of marked left axis deviation such as inferior myocardial infarction or left ventricular hypertrophy

Front 44

Left Posterior Fasicular Block

Back 44

•Mean QRS axis between 90 and 180 degrees in adults with mean QRS duration < 120 ms
•Typically rS complex in leads I and aVL, and qR complexes in leads III and aVF
•Absence of other causes of right axis deviation including lateral myocardial infarction, dextrocardia, or right ventricular hypertrophy

Front 45

LBBB, complete

Back 45

•Mean QRS duration greater than or equal to 120 ms in adults,greater than 100 ms in children 4 to 16 years of age, andgreater than 90 ms in children less than 4 years of age
•Late forces of QRS complex should be negative (i.e terminal S wave) in V1
•Broad notched or slurred R wave in leads I, aVL, V5, andV6 and an occasional RS pattern in V5 and V6 attributed todisplaced transition of QRS complex
•Absent q waves in leads I, V5, and V6, but in the lead aVL,a narrow q wave may be present in the absence of myocardial pathology
•Delayed onset of intrinsicoid deflection (> 60 ms from beginning of QRS complex to peak of R wave) in leads V5 and V6 butnormal in leads V1, V2, and V3, when small initial r waves can be discerned in the above lead.

Front 46

LBBB, incomplete

Back 46

•Mean QRS duration between 110 and 119 ms in adults, between 90 and 100 ms in children 8 to 16 years of age, andbetween 80 and 90 ms in children less than 8 years of age
•Late forces of QRS complex should be negative (i.e terminal S wave) in V1
•Presence of left ventricular hypertrophy pattern
•Delayed onset of intrinsicoid deflection (> 60 ms from beginning of QRS complex to peak of R wave) in leads V4, V5, and V6
•Absent q waves in leads I, V5, and V6

Front 47

Intraventricular conduction disturbance, nonspecific (IVCD)

Back 47

•Mean QRS duration greater than 110 ms in adults, greater than 90ms in children 8 to 16 years of age, and greater than 80 ms in children less than 8 years of age
•Specific criteria for right or left bundle branch block (e.g. delayed onset of intrinsicoid deflection) are not met.

Front 48

Functional (rate-related) aberrancy

Back 48

•Mean QRS duration is greater than 120ms in the setting of rapid heart rates, but returns to normal duration at slower heart rates.

Front 49

Prolonged QT interval

Back 49

•Corrected QT interval (QTc) greater than 450ms in males and 460ms in females
•The corrected QT interval is equal to the actual QT interval divided by the square root of the R-R interval duration measured in seconds

Front 50

Prominent U waves

Back 50

•Amplitude > 1.5mm

Front 51

Digitalis Effect

Back 51

•Sagging concave upward ST-T segment depression
•Shortened QT interval, prolonged PR interval, and prominent U wave
•T wave may be flattened, inverted, or biphasic in morphology

Front 52

Digitalis Toxicity

Back 52

•Most commonly results in atrial tachycardia, atrial fibrillation with complete heart block and accelerated junctional rhythm, second or third degree atrioventricular block, or bi-directional ventricular tachycardia
Note: Digitalis toxicity may be exacerbated by hypokalemia, hypomagnesemia, and hypercalcemia. Cardioversion of atrial fibrillation in the setting of digitalis toxicity can result in prolonged aystolie or ventricular fibrillaton, and therefore, is contraindicated.

Front 53

Antiarrhythmic Drug Effect

Back 53

•Prolonged QT interval
•Prominent U waves
•Non-specific ST-T wave abnormalities

Front 54

Antiarrhythmic Drug Toxicity

Back 54

•Prolonged QT interval
•Ventricular arrhythmias inluding 'Torsade de Pointes'
•Heart Block
•Sinus arrest

Front 55

Hyperkalemia

Back 55

•Tall, peaked, narrow T waves
•Shortened QT interval and ST-T segment depression
•QRS widening and/or bundle branch block
•Bradycardia and sinus arrest
•Ventricular tachycardia and fibrillation

Front 56

Hypokalemia

Back 56

•Prominent U waves
•Prolonged QT interval (occassionally)
•ST-T segment depression and flattened T waves
•Various degrees of atrioventricular block
•Ventricular tachycardia and fibrillation.

Front 57

Hypercalcemia

Back 57

•Shortened QT interval
•May prolong PR interval

Front 58

Hypocalcemia

Back 58

•Prolonged QT interval

Front 59

ASD, secundum

Back 59

•Incomplete right bundle branch block (typical RSR' or rSR' complex in V1 with a QRS duration < 120ms)
•Right axis deviation (mean QRS axis > 100 degrees)
Note: Ostium secundum atrial septal defects comprise approximately 70% of all atrial septal defects.

Front 60

ASD, primum

Back 60

•Incomplete right bundle branch block (usually RSR' complex in V1)
•Left axis deviation (mean QRS axis > -30 degrees)
Note: Ostium primum atrial septal defects comprise approximately 15% of all atrial septal defects. They are associated with cleft anterior mitral valve, mitral regurgitation, and Down's syndrome.

Front 61

Dextrocardia

Back 61

•P wave, QRS complex, and T wave in leads I and aVL are inverted or 'upside down'
•Revere R wave progerssion (R wave amplitude is largest in V1 and gets smaller as you move towards V6)

Front 62

Chronic Lung Disease

Back 62

•Features suggestive of lung disease include right ventricular hypertrophy, right axis deviaton, poor R wave progression, and low voltage

Front 63

Acute Cor Pulmonale (including PE)

Back 63

•S1Q3T3 (large S wave in lead I, pathological Q wave in lead III, and T wave inversion in lead III) is the textbook finding associated with right ventricular dilation and strain, but is present in less than 15-30% of acute pulmonary embolism
•Right axis deviation, right bundle branch block, non-specific ST-T segment abnormalities, and right atrial enlargement (P pulmonale) may also be present.

Front 64

Pericardial Effusion

Back 64

•Low voltage and/or electrical alternans are consistent with (but not very sensitive or specific) a diagnosis or pericardial effusion.

Front 65

Acute Pericarditis

Back 65

•Diffuse ST-T segment elevation with no reciprocal depressions
•PR segment elevation in aVR with PR segment depression in the other limb leads
Note: If there is diffuse ST-T segment elevation in both the inferior (e.g. lead II) and lateral limb leads (e.g. lead I), a more global process (e.g. pericarditis) is typically the etiology. ST-elevation secondary to acute myocardial infarction usually involves more focal elevation in the distribution of a single coronary artery with associated reciprocal ST-T segment depression.

Front 66

Hypertrophic Cardiomyopathy

Back 66

•Abnormal QRS complex characterized by large amplitude QRS (left ventricular hypertrophy), pathological Q waves (pseudoinfarct pattern in the inferior, anterior, or lateral leads), or a tall R wave in V1 simulating right ventricular hypertrophy
•Left axis deviation in approximately 20% of patients
•Nonspecific ST-T segment abnormalities or ST-T segment changes secondary to ventricular hypertrophy
•Left atrial abnormalities
Note: Apical variant of hypertrophic cardiomyopathy gives deep T wave inversions in V4-V6.

Front 67

CNS disorder

Back 67

•Large upright or deeply inverted T waves (usually found in the precordial leads, but also can be diffuse)
•Prolonged QT interval and prominent U waves.

Front 68

Myxedema

Back 68

•Low QRS voltage in all leads and/or electrical alternans
•Sinus bradycardia
•Frequently associated with pericardial effusion

Front 69

Hypothermia

Back 69

•Rhythm is typically Sinus bradycardia or atrial fibrillation
•Prolongation of PR, QRS, and QT intervals
•Presence of Osborne ('J') wave: late upright terminal deflection of the QRS complex that increases in amplitude as temperature declines.

Front 70

Sick Sinus Syndrome

Back 70

•Marked sinus bradycardia, sinus arrest, or sinoatrial exit block
•May also be characterized by prolonged sinus node recovery time after premature atrial complexes or associated with tachybrady syndrome.

Front 71

Atrial or coronary sinus pacing

Back 71

•Pacemaker stimulus followed by atrial depolarization
•If the intrinsic sinoatrial rate falls below the pacemaker rate, then atrial pacemaker spikes will occur at a constant (A-A) interval.

Front 72

Ventricular Demand Pacemaker

Back 72

•Pacemaker stimulus followed by a QRS complex of different morphology than the intrinsic QRS complex
•A pacemaker in VVI mode paces in the ventricle, senses in the ventricle, and inhibits itself from firing if it senses an intrinsic QRS complex.

Front 73

Dual chamber Pacemaker

Back 73

•A pacemaker in DDD mode paces and senses in both the atrium and the ventricle, and inhibits itself from firing if intrinsic atrial or ventricular activity is recognized.

Front 74

Pacemaker Malfunction, not constantly capturing

Back 74

•Pacemaker stimulus without appropriate depolarization (at a time interval when the myocardium is not refractory)
•May be caused by lead fracture, perforation, displacement, or increased pacing threshold secondary to myocardial scar, medications (e.g. flecainide, amiodarone), or electrolyte abnormalities (e.g. hyperkalemia)

Front 75

Pacemaker Malfunction, not constantly sensing

Back 75

•Failure of pacemaker lead to recognize intrinsic depolarization, resulting in attempted pacing at innappropriate intervals (e.g. immediately following a native QRS complex when the myocardium is refractory).